T>4 GRAMINEAE. 



bright green, fine, smooth, short, very narrow loaves; ligule acute, 2 lines 

 long; panicle very long and narrow; branches several at a node, distant, mostly 

 appressed, capillary, scabrous, spikelet-bearing above the middle; pedicels 

 somewhat elavate; spikelets many, 1% to 2 lines long; bracts Linear-subulate, 

 acuminate, nearly equal, 3-nerved, green, exceeding the uppermost braetlet; 

 bractlet 1 line long, smooth and shining, with a tuft of silky hairs at base, 

 irregularly 5-toothed or lacerate at apex; the lower and its flower on a short 

 callus; the upper upon a very hairy internode % as long as the lower; awn 

 arising from near the base of the bractlet and twice its length, very slender 

 and long-exserted. — (Aira elongata Hook.) 



Moist places along the coast northward to Oregon. Var. ciliata Vasey. 

 Stems 2 to 2% ft. high; ligule 4 lines long; blades involute and softer; panicle 

 often 12 in. long; awns longer than in the type. — Lake Pilarcitos; Olema. 

 June- Aug. Var. tenuis Vasey. Very small plant, 3 to 4 in. high, with soft, 

 hairdike, bright-green foliage; ligule long, white; panicle racemose, 1 to 2 

 in. long; branches appressed, with few spikelets. — Moist places, Santa Clara 

 Co. May. 



3. D. calycina Presl. Tickle-grass. Annual; stems slender, from a few 

 inches to 2 ft. high, simple, often growing in dense masses, rarely geniculate 

 and sparingly branched below; leaves few, short, narrow and ephemeral; ligule 

 1 to li/> lines long, acuminate; panicle simple, very loose and open or narrow, 

 about Ya the length of the stem; branches mostly in 3s below, in -pairs or 

 solitary above, bearing few (about 5) spikelets upon the upper part, naked 

 below; spikelets 2% to 4VL> lines long; lower flower on a short callus, its 

 bractlet overlapping that of the upper flower; bractlet about 1 line long, hairy 

 below, shining above, 5-nerved; apex emarginate, with 4 minutely ciliate teeth; 

 awn inserted below the middle, about 3 times as long as the bractlet, light 

 brown, twisted below and bent near the middle. — (Aira danthonioides of Bot. 

 Calif.) 



Common in the San Francisco Bay region and elsewhere in the State, on 

 poor clay soils: St. Helena; Montezuma Hills; Kenwood; Santa Cruz. Apr.- 

 June. 



19. TRISETUM Pers. Oat-grass. 



Leaf-blades flat. Panicle usually open, narrow, more or less drooping above; 

 branches in whorls, slender, erect, spreading or drooping. Spikelets 2 to 

 5-flowered. Bracts mostly shorter than the whole spikelet, unequal, keeled, 

 membranaceous; margins scarious; lower bract 1 to 3, upper 3-nerved; rachilla 

 extending beyond the insertion of the uppermost flower-enclosing bractlet, and 

 terminated by an empty bractlet or a slender awn. Flower-enclosing bractlets 

 like the bracts in texture, keeled, 5-nerved, acuminate, ending in two long, 

 subulate teeth, with a long, bent and twisted awn arising from between them; 

 palea 2-nerved ami 2-toothed. Ovary hairy or smooth; stigmas almost ses- 

 sile. Achene smooth, not furrowed. (Latin tris, three, and saeta, a bristle, 

 referring to the awndike points which terminate the bractlet in many species.) 



Panicle-branches more or less sprei ding or sub-erect. 



Spikelets large-, <> ;<> 12 lines long, 2 to 3 lines wide, 3 to 8-fiowered, resembling those 

 of a Bromus; rachilla nearly glabrous, bractlets hirsute 1. T. barbatum. 



Spikelets small, .? to 6 lines long, about 1 line wide. J to .^ (rarely 4 ) -flowered ; rachilla 

 Clothed with long hails, bractlets sub-glabrous; lower bract about l /j as long as 



the upper; panicle-branches spikelet-bearing on the upper half.... J. J. nutkaense. 



